Correspondence to
Dr Summer Sherburne Hawkins, Harvard School of Public Health, Harvard Center for Population and Development Studies, 9 Bow
Street, Cambridge, MA 02138, USA; shawkins{at}hsph.harvard.edu

Accepted 7 September 2012

Published Online First 19 October 2012

Abstract

Objectives Despite the passage of state laws promoting breast feeding, a formal evaluation has not yet been conducted to test whether
and/or what type of laws may increase breast feeding. The enactment of breastfeeding laws in different states in the USA creates
a natural experiment. We examined the impact of state breastfeeding laws on breastfeeding initiation and duration as well
as on disparities in these infant feeding practices.

Methods Using data from the Pregnancy Risk Assessment Monitoring System, we conducted differences-in-differences models to examine
breastfeeding status before and after the institution of laws between 2000 and 2008 among 326 263 mothers from 32 states in
the USA. For each mother, we coded the presence of two types of state breastfeeding laws. Mothers reported whether they ever
breast fed or pumped breast milk (breastfeeding initiation) and, if so, how long they continued. We defined breastfeeding
duration as continuing to breast feed for ≥4 weeks.

Results Breastfeeding initiation was 1.7 percentage points higher in states with new laws to provide break time and private space
for breastfeeding employees (p=0.01), particularly among Hispanic mothers (adjusted coefficient 0.058). While there was no
overall effect of laws permitting mothers to breast feed in any location, among Black mothers we observed increases in breastfeeding
initiation (adjusted coefficient 0.056). Effects on breastfeeding duration were in the same direction, but slightly weaker.

Conclusions State laws that support breast feeding appear to increase breastfeeding rates. Most of these gains were observed among Hispanic
and Black women and women of lower educational attainment suggesting that such state laws may help reduce disparities in breast
feeding.